so basically I have my protein of interest and I wish to see if it binds to a certain receptor...I need to do an ELISA to see if it does and I have done a number of ELISAS in the past using the above protocol...this one is different though because as oppsed to protein, antibody, secondary antibody..I will have protein, protein, antibody, secondary antibody..so my question is what steps would I have to modify I'm thinking at step 1: add my "receptor protein of interest" and then at step 6: add my protein that I wish to see if it binds to and then continue on with same steps...has anyone done a similar protocol before?...Ideally how much second protein do I need to add, would I just need to titrate out different amounts?